Sternum fixation device and method

ABSTRACT

An apparatus and technique for infernally securing a plurality of bone segments together. The device incorporates a plate-like structure stabilizing the fracture and integrated fasteners to attach straps circumscribing the bone segments.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.16/208,707, filed Dec. 4, 2018, which is a divisional of U.S. patentapplication Ser. No. 14/178,017, filed Feb. 11, 2014, that claims thebenefit of provisional of U.S. Provisional Application No. 61/801,005filed Mar. 15, 2013, all of which are incorporated herein in theirentirety.

FIELD OF THE INVENTION

This invention relates to an implantable sternum fixation device tosecure and aid in the healing of a surgically cut or fractured sternum.

BACKGROUND OF THE INVENTION

Over the last 30 years Open Reduction Internal Fixation (ORIF) withRigid Internal Fixation (RIF) has become accepted as the standard ofcare for treating many types of fractures helping patients painlesslyreturn to pre-injury function earlier and more reliably thanconventional treatment methods such as casting, bracing, interosseouswiring and cerclage wiring. In addition, when properly applied RIFimproves the reestablishment of pre-fracture anatomical bone alignmentpromoting more reliable infection free healing. Besides the provenbenefits in trauma care, ORIF is an acceptable method of repositioningbones in elective procedures and repairing bones surgically cut orfractured when necessary to gain surgical access to perform a primaryprocedure. Such is the case in open-heart surgery where the sternum issurgically cut to gain access to cardiovascular structures containedwithin the chest wall. In such cases the sternum is surgically cut alongthe midline of the long axis of the bone separating the sternum and theassociated rib cage in half sections left and right.

The standard method for reconstructing the surgically cut sternum is theplacement of stainless steel wires circumferentially (cerclage) aroundthe sternum segments and compressing together by twisting the wirestight to hold the surgically cut bone ends together approximating thepre-cut anatomical position of the sternum and chest wall. In most caseswire fixation has proven to be a successful and cost effective method ofrepairing the cut sternum with minimal reports of infection andnon-union. The literature describes complication rates (infection and/ornon-union) as high as 8%. Patients that incur complications, however,can endure significant pain and resolving their issues has provendifficult, time consuming, and expensive.

Patients with certain underlying health issues are predisposed tocomplications and a delayed healing response. For instance, perhaps mostsignificantly, certain cardiovascular patients with multiple healthissues including, as examples, COPD, diabetes, and/or suppressed immuneresponse that may delay or prevent healing, exhibit a propensity forpost-operative infection, hardware failure and/or nonunion of thesternum. Other factors, such as age, poor diet, smoking, alcohol abuseand/or drug use, can also adversely affect healing. Many of thesepatients exhibit diseased bone that is weak and may lack sufficientcortical density and thickness.

Over the years, numerous attempts have been made to improve a method forfixing the sternum, but most devices are designed to address the sternumafter complications have arisen and are not intended to preventcomplications by providing an improved primary solution. Furthermore,many of the commonly marketed products tend to be over engineered,complicated and time-consuming to implant. There are also a host ofdevices that do not appropriately address the complexities of the humananatomy and the demands such fixation must address in clinicalapplication. Those devices tend to offer little to no benefit over wirefixation and may lead to unexpected and unintended complications beyondwhat is known from wire fixation.

The sternum is a flat bone with a thin cortex shell (dense outer bonelayer). Cortical density and thickness are important factors with screwfixation techniques as they provide resistance against pullout whenscrews are tightened as purchase is achieved by the threads compactingand resting in bone. Cortical density and thickness are also importantfactors in cerclage wire fixation as stability relies on wirescompressing directly against the cortex to maintain secure fixation.

An implant construct must provide and maintain sufficient stabilizationfor a duration long enough to allow bone healing to occur. If healingdoes not occur within an acceptable timeframe hardware loosening oftenleading to hardware failure becomes an increasing risk. This principlealso applies to sternum fixation. In the patient population prone todelayed healing and increased risk of complication, cerclage wirefixation may be contraindicated. In such cases, fixation failure occursdue to broken or loosened wires. In some instances, such wire (loosen bycutting through the sternum cortex (commonly referred to as the “cheesegrater effect”), which leads to mobility of the bone fragments,potential fracture of the sternum, and almost certain infection.Frequently when patients exhibit failed cerclage wire fixation, radicaldebridement of soft tissue and bone is necessary and subsequentreconstruction resembles a salvage procedure.

Coughing, which is a very common post-operative occurrence, especiallywith patients with COPD or pneumonia, generates high peak forces thatact on the repaired sternum, thus increasing the incidence of failure ofcerclage wire, as well.

Uncontrolled motion between two fractured bone fragments may alsocontribute to an increased incidence of infection. As such, the fixationconstruct chosen must control motion under functional loading conditionsto create a favorable healing situation. Opinions have varied over theyears as to how much rigidity is desirable in a fixation construct.Historically, it was considered a treatment goal to create a motion-freeinterface between two bone fragments which can be achieved bycompressing the fractured or severed bone surfaces in direct opposition,eliminating all motion and encouraging direct healing without theformation of callus. However, it has now been realized, through thepassage of time and the gaining of valuable experience in this area,that the need for extreme rigidity, and thus the elimination of allmotion in this situation, is not necessary nor the prevention of callusformation. In essence, it has been found that fixation constructs thatare substantially more rigid than the bones they are holding can lead toa condition known as stress shielding that fosters poor bone quality andstrength giving rise to potential secondary complications includingre-fracture. Load-sharing by implants is increasingly gaining favor asit is thought to promote healthier and stronger bone.

Another consideration is whether fixation implants can and should beleft in the body long-term or permanently. There are many factors toconsider such as patient age, the anatomical location of the implant,and the difficulty in removal. Generally, however, most surgeons preferto leave fixation implants in vivo permanently and not perform asecondary procedure for removal whenever possible. Many cases offixation implant removal result from patient complaints of discomfort,irritation, and palpability. An ideal implant design is one that can beleft in the body permanently and causes little or no pain or discomfortto the patient during the healing phase and beyond.

The implant material is another major consideration in making the bestimplant fixation choice. It is vitally important (for clear reasons)that the implant be biologically stable and not cause irritation oranother undesirable response while in the body. Furthermore,consideration should be given to an implant's potential effect ondiagnostic, imaging, monitoring and other therapeutic technologiesnecessary to deliver post-operative patient care.

The speed and ease of installation are important considerations to makewhen choosing an implant fixation construct. Cardiovascular surgeons arenot orthopedists and therefore not routinely familiar with drills,screwdrivers and other “bone carpentry” tools. Many sternum closuredevices currently offered require such items as they are based onorthopedic plate and screw technology. These devices typically requiremultiple instruments to apply, have numerous individual component parts,and take an excessive amount of time to apply adding additional time,complexity and cost to the surgery.

The speed and ease of implant removal are also critical factors whenchoosing a fixation implant construct, especially in the case of atarget sternum whereby emergency surgical re-access may be requiredshould the patient incur a life-threatening health event necessitatingsurgical reentry of the chest wall. If a device requires specialinstruments to remove or has become biologically imbedded in the softtissues and/or bone, valuable time can be lost dealing with locatingremoval instrumentation and exposing and removing the implants.

Additionally, the cost of an implant device construct must be reasonableand not add significantly to the overall cost of performing surgery. Inthe case of the sternum cerclage wire fixation, the material cost ofsurgical wire is insignificant. Plate and screw constructs for sternalclosure range in price but easily can cost $3,000 to $5,000 per device.In addition, there are disposable components, such as drill bits, etc.,that add to the cost and complexity of surgery. All knownsternum-plating sets are configured as reusable trays containing anassortment of implants and reusable instruments requiring sterilization,cleaning, and restocking and storage between each use requiringadditional costs and labor.

Typical sternal fixation devices include rigid-plate constructs withelaborate locking screws whereby the screws simultaneously thread intothe plate and sternum which prevents the screws from becoming detachedfrom the plate in the event they strip and become dislodged from thesternal bone. The instructions for use of such systems (such asavailable from Synthes and Biomet Microfixation) typically recommend aminimum of three plates and the placement of multiple screws to affixeach plate to each independent bone segment. The plates are spaced andimplanted along the anterior facing sternal surface midline straddlingthe saw cut with screws inserted into the sternum on both sides of thecut. Synthes offers a plate configuration that comprises of two halvesjoined together in the center with a removable u-shaped pin. Ifemergency re-access becomes necessary, the operator may remove the pinsand separate the sternum and associated rib attachments left and rightgiving immediate access through the chest wall. However, uncoupling theplate assembly only mobilizes the underlying bone while the bone remainsunhealed. If reentry is attempted after the soft tissue and/or boneshave partially or fully united, simply removing the pins will not allowimmediate re-access. In such instances, the bulky metal plates wouldinterfere with a saw cut being made through the sternum in theconventional way without first removing the plates and screws, addingtime and placing the patient at additional risk if access through thechest wall is urgently needed. Such screw-secured implants are also verytime-consuming to implant and costly. Furthermore, their excessivelyrigid construction can result in stress shielding leading to poor bonequality and strength or delayed healing. Biomet Microfixation attemptsto overcome the limitation of the Synthes design by making their platescuttable in the center; however, a special cutting instrument is stillrequired to cut and remove sections of implanted plates.

In another variation of a prior device, reduced stress shielding hasbeen provided through the utilization of braided cables throughsterna-positioned cannulated metallic grommets. Unfortunately, though,this alternative still requires excessive operating time and askill-dependent implantation procedure. The cable is laced along thesternum like laces on a shoe and tightened with a special cable crimpinginstrument. The process for installation is too cumbersome and timeconsuming and getting the bone segments back into anatomical positionhas proven too difficult for widespread, reliable use.

Self locking fasteners, such as or similar to cable ties or zip tiesplaced circumferentially around the sternum through the intercostalspaces provide improved simplicity and potential time savings comparedto wire fixation, but do not provide enough stability to adequatelyimmobilize the bone segments sufficiently to achieve desirable andreliable healing for all patients. Like wire fixation, the zip tiefixation method disregards the significant forces loading on the sternumand is not an adequate solution for, in particular, at risk patients.Therefore, it appears to be a potentially more convenient way to achievethe same benefits of cerclage wiring.

Another available device designed for closing the chest wall and holdingthe sternum together following median sternotomy consists of amechanical clamp that cleats around the sternum with extensions passingthrough the intercostal spaces. When used in series, these metallicclamps sold by KLS Martin compress the sternum together. The clamps arelarge, excessively rigid and frequently uncomfortable and irritating tothe patient frequently necessitating post-operative removal, as well ascomparatively costly. They also interfere with common imagingtechnologies including x-ray, CT and Mill.

There is a device available from Acute Innovations called Acutie thatsupposedly enhances the strength and stability of a cerclage wireconstruct. Surgical wire is passed around the sternum through theintercostal spaces and inserted through slots in a stainless steelplate, then tensioned and crimped. The method calls for multiple platesspaced along the anterior aspect of the sternum. The plates aresubstantially stronger than the bone and only prevent wire abrasion on alimited surface area of the sternum thus would seem to provide littlebenefit over wire fixation alone. The potential for wire to loosen,break and/or cut through bone is not entirely eliminated and might evenbe enhanced due to the plate stiffness transferring more load to thewire section in direct contact with bone.

Other identified competitive offerings tend to follow a plate and screwapproach to fixing the sternum, typically with cuttable struts acrossthe central section facilitating removal. None of them appear to offersignificant benefits over each other and due to the significant forcesthat act on the sternum under extreme functional loading all presentsimilar risks of complication due to inadequate load distribution anddissipation of forces acting on the chest wall.

A need thus exists for an inexpensive sternum fixation device that iseasy to implant, achieves and maintains proper anatomical reduction,provides sufficient stiffness and stability to withstand the dynamicfunctional loads acting on the sternum under extreme physiologicalconditions, is load sharing by design to allow native bone to absorblimited forces to promote quality bone healing, is well tolerated bypatients, poses no risk to the surrounding soft and hard tissues andother structures, can be left in the body long term allows quick accessto the chest cavity by conventional methods, does not interfere withother diagnostic or therapeutic treatment during and after surgery, andcan be quickly and easily removed should surgical reentry be necessary.To date, the sternum fixation industry has yet to provide such abeneficial alternative to the current devices described above.

BRIEF SUMMARY OF THE INVENTION

The invention disclosed involves a novel method referred herein as“circumfixation” device and method. This novel approach to fixationachieves a better fixation construct than previously available for avariety of clinical indications. In the case of sternum closurefixation, circumfixation device and method represents the perfect choiceas it precisely addresses the prerequisites of sufficient rigidity, easeand speed of application and removal, biological stability, welltolerated, non-obstructive to other diagnostic and therapeutictechnologies while remaining cost beneficial.

The inventive sternum circumfixation device and method can be bestdescribed as a type of internally placed splint comprising at least onespecially designed plate-like body and a plurality of correspondingstrap-like fastening members, herein also referred to as “lockingfasteners.” The body of the device, herein also referred to as “plate,”is shaped to conform to a target patient's sternum and is configured tobe placed along its anterior surface and secured in position by the useof zip tie-like fasteners that pass behind the sternum (the posteriorside thereof) through the intercostal spaces and locked to the platethrough special locking slots incorporated into the plate. The idealmaterial composition is a thermoplastic polymer such as polyether etherketone (PEEK) because of its high strength and stiffness that can mimichuman bone and its ability to be adapted to the irregular surface of thesternum and its high fatigue strength that permits prolonged loadsharing common during a delayed healing response. The material'sstrength and stiffness allows the plate to be made in a low-profileconfiguration and to more closely replicate the strength and elasticityof the human sternum while being completely biologically compatible andwell tolerated by the target patient. It has been realized that one of alarge singular plate or singular plate having any number of correlatedcontours to the sternum shape and configuration allows for betteranatomical restoration and is necessary to counteract the dynamic forcesof tension, torsion and shear acting on the sternum, especially thoseacting along the forward or anterior facing surface of the sternum. Theuse of fasteners instead of screws or wires creates a more reliablefixation construct, and together with the plate they allow for loadsharing and promote micro movement in the healing zone thoughtbeneficial to promoting healthy healing of bone. In addition, fastenerscan be applied quickly with minimal instrumentation and easily removedwith common surgical scissors. Furthermore, whereas screws rely onhealthy and dense bone for their threads to maintain grip and sternumbone has been shown to have poor cortical density and thickness that maynot be sufficient to prevent screw strip out or wire cut out under theextreme loads common to the sternum during normal physiologicalfunction, the inventive devices places the loading over a larger surfacearea of cortical bone mass. Thus, the important considerations are theshape of the plate and the capability thereof of relating to the sternumsufficiently in shape to accord a comfortable and capable protectiveshield in combination with a strong, yet comfortable attachmentcomponent that runs along the posterior surface of the subject sternumand connects to both ends of the plate around a single intercostalspace. The utilization of easily manipulated connection devices toreliably attach the attachment component on demand, and that alsoremains reliably in place within the structure of the plate for anundetermined period of time after implantation without exhibiting anyappreciable loss of connection strength, additionally provides a highlydesirable repair mechanism in this area.

Circumfixation provides the additional advantage of providing abiomechanical and biological approach to bone healing. It isappropriately termed “biomechanical” because this method considers notjust the forces acting on the bone but the fundamental purpose of thebone itself. The fixation allows the bone to function in the manner itwas intended while maintaining it sufficiently stable to achievedesirable and predictable healing. The term “biologic” applies becauseit mimics the strength, stiffness, and elasticity of the target bonewhile allowing the body's natural healing abilities to take effect.While spanning the sternum, the circumfixator plate rests on torsionrails or “piers” that add stiffness and minimize direct contact with thebone surface and thus which promotes the free flow of fluids andcellular activity at the healing site beneath the plate. Furthermore,the inert nature of the implant does not retard or interfere withdesirable healing. It also avoids unnecessary trauma to bone thatresults from drilling and placing foreign bodies therein (such as screwsand/or cables, as non-limiting examples). The sternum circumfixationconstruct applies desirable compression along the entire bone fragmentinterface which enhances healing while controlling movement and therange of dynamic forces acting on but not eliminating micro-motionthought to be beneficial to the healing process. The splinting nature ofthe circumfixation construct promotes load sharing of extreme forcesalong the entire geometry of the plate in a similar way as exhibited bya healthy uncut or non-fractured bone (sternum). This action thusshields and protects the underlying bone from overloading while allowingsome loading to transfer to the bone thought to be the ideal scenariofor promoting the healthy healing of bone.

The sternum circumfixation construct is also safe and well tolerated bytarget patients. Unlike plates, screws, and/or clamps, there are nosharp edges or pointed tips that could seriously harm patients if theywere to fall or suffer trauma to the sternum region either during thehealing phase or after healing is complete. This new device thus alsoavoids the overly rigid metallic constructs that create stress risers inthe surrounding bone. Overall, then, the inventive device furtherreduces the likelihood of secondary bone fractures that can occur as aresult of overloading at the location of the stress riser. As mentionedearlier, many cardiothoracic patients have co-morbidities making thempredisposed to infection, to delayed healing, and to poor bone qualityand blood perfusion. For these high-risk patients especially, sternumcircumfixation is a superior choice as a short term, long term, orpermanent implantation period. The flush smooth surface of the sternumcircumfixator and fasteners causes no irritation to the surroundingtissues and bone. The lack of metallic components, which are required ofall known prior sternum repair devices with the exception of zip tiefasteners, also reduces the patient's sensitivity to cold temperatures,eliminates the potential of complications due to metal sensitivity andwill not interfere with imaging and other diagnostic and therapeutictreatments. Furthermore, some patients who undergo open chest proceduresmay later require cardiopulmonary resuscitation (CPR) and the presenceof a circumfixator would not interfere with performing such a procedurewhereas metallic devices could make such a procedure difficult orimpossible to perform and lead to other unintended consequences such asimplant loosening or breakage, infection and/or bone fracture.

Accordingly, the invention thus encompasses herein a sternal splint topromote healing and protection of a person's sternal anatomy subsequentto a sternotomy, wherein said sternal body includes a sternum bonehaving an upper surface and underside sternal bone and a plurality ofintercostal spaces between said person's ribs, wherein said splint is asingular plate having front and back ends construct spanning at least aportion of said upper surface and secured thereto with at least onelocking fastener passing through said at least one intercostal spacewith attachment at both said front and back ends of said plate. Such aconfiguration may include a single plate that covers a portion of saidsternum such that more than one fastener is utilized and said fastenerspass through more than one intercostal space between said person's ribs.Additionally, more than one such plate may be utilized at a time spacedaccordingly along said person's sternal body. Such a plate (or plates)and fastener (or fasteners) promote weight load bearing to the uppersurface of the sternal body as well as stress load dissipation acrossthe plate entirety and underlying sternal bone to, again, provide asuitable healing situation after a sternotomy. Another manner ofdescribing such an inventive device is as a bone plate containing atleast locking mechanism connecting said plate with at least oneindependently placed locking fastener, wherein said at least one lockingfastener and said plate form an implantable bone splint (to compressbone fragments together, for example) and wherein each of said at leastone independent locking fasteners is adjustable for different tensioninglevels.

In greater detail, then, one possible embodiment for this invention isan internal bone splint comprising: an elongated plate having a heightgreater than a width, said plate having a right side, a left side, atop, a bottom, front, a back; a plurality of apertures positioned withinsaid elongated plate, extending through from said front side to saidback side; a plurality of fastener straps configured to engage saidapertures; and a plurality of self-locking mechanisms whereas each selflocking mechanism is configured to allow a said fastener strap to passthrough a said aperture when said fastener strap is passed from saidback to said front direction, but resist a said fastener strap frompassing through said aperture from said front to said back direction;wherein said back of said elongated plate includes protruding torsionrails. Additionally, the inventive device encompasses the same bonesplint wherein said plate possesses a plurality of protrusions alongsaid right and left sides, wherein each said aperture is positionedwithin a protrusion. The inventive device may further comprise acannulated tensioning handle configured to receive a said fastenerproviding the operator a simple and convenient means of tensioninglocking fasteners attached to the plate.

Alternatively, the invention may encompass an internal bone splintcomprising: a first elongated plate and a second elongated plate, eachplate having a height greater than a width, said plate having a rightside, a left side, a top, a bottom, front, a back; a plurality ofapertures positioned within said first elongated plate, extendingthrough from said front side to said back side; a plurality of fastenerstraps configured to engage said apertures, said fastener strapsattached at one end to said second plate; and a plurality ofself-locking mechanisms whereas each self locking mechanism isconfigured to allow a said fastener strap to pass through a saidaperture when said fastener strap is passed from said back to said frontdirection, but resist a said fastener strap from passing through saidaperture from said front to said back direction; wherein said back ofsaid elongated plate includes protruding torsion rails.

As another alternative, the invention may encompass a internal bonesplint comprising a rigid or semi-rigid plate having a right side, aleft side, a top, a bottom, a front, and a back; at least one aperturepositioned within said elongated plate along either said right or saidleft side and extending through from said front side to said back side;at least one fastener strap configured to engage said at least oneaperture; and at least one locking mechanism present adjacent to saidaperture, wherein each locking mechanism is configured to allow said atleast one fastener strap to pass through said at least one aperture whensaid at least one fastener strap is passed from said back of said plateto said front direction, but configured simultaneously to resist said atleast one fastener strap from passing through said aperture from saidfront to said back direction; and wherein said strap is retained on theopposite side of said aperture by a stationary retention component.Furthermore, such a structure may also include a configuration whereinsaid plate includes at least one protrusions along said right and leftsides, wherein each of said at least one aperture is positioned withinsaid at least one protrusion, and wherein each aperture includes atleast one fastener and at least one locking mechanism.

Also encompassed herein is a self locking fastener having a channelextending the length of said fastener through which a guide wire maypass, wherein said guide wire has a first end and a second end. Thefastener may further comprise a handle, said handle attached to saidsecond end of said wire.

Further encompassed within this invention is a method of internallybracing two portions of a sternum of a patient after a sternotomycomprising: placing a plurality of self locking fastener strap aroundthe posterior of said sternum; placing a plate upon the anterior surfaceof said sternum, said plate having a plurality of apertures configuredto allow the passing of a said self locking fastener strap in a onedirection but resist the passing of a said self locking fastener in anopposite direction; passing each free end of each said fastener strapthrough a said aperture; placing a cannulated tensioning handle on asaid free end of a said fastener strap; tightening said fastener strapto a desired tension; and cutting each said free end of each saidfastener strap flush with said plate.

Thus, overall, the invention may also encompass a method of internallybracing two portions of a sternum of a patient after a sternotomyutilizing any of the above-describing and herein further describedstructures for such effect. As such, the inventive device may permit asuitable protective/healing method for a target patient by providing theinventive to a splint to the sternum of such a patient and utilizing theinventive fasteners described above to secure the splint around thesubject sternum.

The invention will be further and more succinctly described below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a sternum having a longitudinal cut.

FIG. 2 is a front view of a first embodiment of the invention.

FIG. 3A is a rear view of the invention showing partially formed torsionrails and perforations.

FIG. 3B shows a right side view of the invention of FIG. 3A.

FIG. 4 shows a rear view of the invention showing of FIG. 3A.

FIG. 5 shows a rear view of the male plate portion of a secondembodiment of the invention.

FIG. 6 shows a rear view of the female plate portion of a secondembodiment of the invention.

FIG. 7 shows a front view of the invention having a contour transitionon its underlying surface to conform at the sternal angle being thejunction of the sternal body and the manubrium.

FIG. 8 shows a front view of an embodiment of the invention.

FIG. 9 shows a single ended locking fastener of an embodiment of theinvention.

FIG. 10 shows a double ended locking fastener of an embodiment of theinvention.

FIG. 11 shows a cannulated tensioning handle of an embodiment of theinvention.

FIG. 12 shows a rear view of an embodiment of the invention.

FIG. 13 shows a female portion of an two plate embodiment of theinvention.

FIG. 14 shows a male portion of an two plate embodiment of theinvention.

FIG. 15 shows an embodiment of the invention having a plurality ofapertures spaced in close proximity along each side of the plate.

FIG. 16 is a section view taken along line 16-16 of FIG. 2.

FIG. 17 shows an embodiment of the invention in which the lockingfastener, in this case a double ended locking fastener, possesses achannel through which a guide wire may pass.

FIG. 18 shows a single headed embodiment of the locking fastener havinga channel through which a guide wire may pass.

FIG. 19 shows a front view of a single ended embodiment of the lockingfastener having a channel through which a guide wire may pass in whichone end possesses a self locking mechanism to engage the lockingfastener.

FIG. 20 shows a section view of a single ended embodiment of the lockingfastener having a channel through which a guide wire may pass in whichone end possesses a self locking mechanism to engage the fastener straptaken on line 20-20 of FIG. 19.

FIG. 21A shows a perspective view of an embodiment of the lockingfastener having a round profile.

FIG. 21B shows a perspective view of an embodiment of the lockingfastener having a rectangular profile.

FIG. 22A shows a perspective view of the end of the locking fastenerhaving a square pyramid shape.

FIG. 22B shows a perspective view of the end of the locking fastenerhaving a triangular pyramid shape.

FIG. 22C shows a perspective view of the end of the locking fastenerhaving a conical shape.

FIG. 23 shows a front view of an insertion tool with a mechanicalinsertion probe that allows the precise control and manipulation of alocking fastener for guidance upon human insertion of said fastener anembodiment of the invention.

FIG. 24 shows a front view of an insertion tool with a mechanicalinsertion probe installed within a double ended locking fastener anembodiment of the invention.

FIG. 25 shows an embodiment of the invention having a plate with nonlocking apertures and a separate locking nut engaging a fastener strap.

FIG. 26 shows a perspective view of the locking nut.

FIG. 27 shows a top view of a locking nut.

FIG. 28 shows a section view of a locking nut taken on line 28-28 ofFIG. 27.

FIG. 29 is a perspective view of a multi-protrusion embodiment of theinvention.

FIG. 30 is an exploded view of the embodiment of FIG. 29.

FIG. 31 is a rear view of the embodiment of FIG. 29.

FIG. 32 shows a perspective view of a fastener of the invention.

FIG. 33 shows perspective view of a fastener of the invention with astationary retention device attached thereto.

FIG. 34 is a perspective view of an inventive revolving lockingmechanism.

FIG. 34A shows a cross-sectional view of the mechanism of FIG. 34.

FIG. 35 is a perspective view of a single-protrusion bone splint of theinvention.

FIG. 35A is a perspective cross-sectional view of the embodiment of FIG.35.

FIG. 36 is a perspective view of a double-protrusion bone splint of theinvention.

FIG. 37 is a perspective view of a bone splint including a secondarylocking mechanism.

FIG. 37A is a side cross-sectional view of the embodiment of FIG. 37.

FIG. 38 shows a perspective view of a cam-type locking mechanism forutilization with an inv.

FIG. 38A is an exploded view of the embodiment of FIG. 38.

FIG. 39 is an top view of the bottom portion of the embodiment of FIG.39.

FIG. 40 is a bottom view of the bottom portion of the embodiment of FIG.38.

FIG. 41 is a side view of the bottom portion of the embodiment of FIG.38.

FIG. 42 is a perspective view of the cam gear of the embodiment of FIG.38.

FIG. 43 is a bottom perspective view of the top plate of the embodimentof FIG. 38.

FIG. 44 is a side view of the top plate of the embodiment of FIG. 38.

FIG. 45 is a top view of the top plate of the embodiment of FIG. 38.

FIG. 46 is a perspective top view of a fixed angle auxiliary lockingmechanism for utilization with an inventive bone splint.

FIG. 47 shows a side view of the embodiment of FIG. 46.

DETAILED DESCRIPTION OF THE DRAWINGS AND PREFERRED EMBODIMENTS OF THEINVENTION

The plate and fastener assembly must be sufficiently strong to withstandthe biomechanical forces typical under normal and severe functionalloading conditions. In the preferred embodiment, the implant materialwould be biocompatible, light weight, radiolucent and easily removableshould emergent surgical re-entry through the chest wall be necessary.An ideal method of removal would be the ability to release the fixationwith a common pair of surgical scissors by cutting through the fastenersallowing the plate and fasteners to be quickly and easily removed.

The purpose of this invention is to provide an improved implantablemedical device and technique to repair and heal a surgically cut orfractured sternum and surrounding soft tissues with the goal to restorepreoperative anatomical form and function and bony union though healing.The plate is thought to be semi-rigid allowing for flexing of the thoraxduring breathing, coughing and other physiological movements whilemaintaining anatomical positioning of the bony fragments during thehealing phase. The device assembly is intended to be easily applied andremoved if emergent re-access is indicated. The device is intended toreduce post-operative pain and allow early post operative mobilizationof the patient which could lead to earlier rehabilitation and discharge,while reducing the potential for infection and the contraction ofhospital acquired pathogens. The device is intended to be biocompatibleallowing it to remain in the body permanently. The device is intended tobe inert and radiolucent causing no interference with any testing,diagnostic or imaging technology applied to the patient postoperatively.

Many cardiac surgical procedures require passage through the chest wallto access the vital organs contained in the inner cavity. Surgicalaccess is typically gained by cutting the sternum in half with asurgical saw along its long access (median sternotomy) allowing theseparation of the chest wall and rig cage left and right.

A sternum closure device is designed to reduce and maintain the chestwall in anatomical position following open chest procedures in which amedian sternotomy was performed.

Additionally, the proposed invention could be designed to elutetherapeutic agents such as antimicrobials and/or bone healing agentslike stem cells or BMPs. Alternatively, the device could be coated withsaid agents to promote infection free healing. The device could also beimbedded with smart technology to perform various diagnostic and/orclinical tasks or provide dockage for other implantable technologies.One example is the potential to embed an implantable bone stimulationcapability to aid and assist bone healing.

While Circumfixation is primarily intended for the purpose of assistingin the healing of surgically cut and fractured bone, it could also be avaluable method for surgically implanting and hosting a range ofundefined therapeutic and diagnostic technologies and agentsunassociated with fracture repair that might benefit from in vivodelivery in anatomical locations not limited to the sternum.

The invention comprises a rigid or semi-rigid plate in the general shapeof the human sternum that is placed over the sternum for the purpose ofsplinting the sternum into position for healing following a surgical cutto the sternum separating it into left and right halves longitudinallytechnically described as sternotomy. The device might also be applied tosecure the sternum in position following traumatic injury resulting infracture. The plate has spaced slots along the lateral edges of theplate to accommodate the placement of fastener straps that are passedbehind the sternum and threaded through opposing slots. Some or all ofthe slots can be configured with a locking mechanism that allows thefasteners to be affixed to the plate when tensioned. The slots arespaced to overlay the gaps between ribs known as intercostal spacesallowing for the fasteners and plate to circumferentially surround thesternum and hold it in secure position to promote reduced pain or painfree bone and soft tissue healing mitigating many potentialcomplications observed with conventional methods.

The plate might also be configured with a capability to delivertherapeutic agents such as antibiotics, pain control, cancer treatment,bone healing growth factors such as stem cells or BMPs, etc. The platemight also be coated with antibiotics or bone healing compounds andagents.

Circumfixation could have applications in rib fracture fixation,clavicle fracture fixation, scapula fracture fixation, proximal anddistal femur fixation, proximal and distal tibia fixation, fibulafixation, proximal and distal humerus fixation, proximal and distalradius and ulna fixation, wrist bracing and/or reconstruction, anklebracing and/or reconstruction, spinal bracing and/or reconstruction,pediatric fracture fixation, peri-prosthetic fracture management andfixation, veterinary fracture fixation and possibly other unidentifiedapplications. The invention comprises of a plate contoured to liepassively against the forward facing aspect of the human sternum whenplaced directly on the sternum's irregular surface, zip tie-likefasteners secure around the sternum, securing the plate to the sternum.Attachable cannulated handles facilitate manipulating and tensioning thefasteners. The sternum plate could be made of a biocompatiblethermoplastic polymer material like PEEK, PEAK, PAEK, UHMWPE, Silicone,ULTEM, RADEL, PPO, PPS, Nitinol, Stainless Steel, Titanium alloy,oxidized zirconium, ceramic, cobalt chrome, resorbable polymers, carbonfiber, carbon fiber reinforced PEEK or collagen. The sternum plateshould be thin (preferably 1-10 mm thick) slightly tapered in therelative shape of a human sternum, slightly parabolic or possiblyrectangular in the general dimensions to resemble the human sternum. Theplate should have a series of spaced or contiguous slots (holes) placednear the outer or distal edges in direct opposition to each other alongthe long axis of the plate. The purpose of the slots is to provide adocking port for the fastener ends to attach to the plate. The slotscontain locking mechanisms that secure around the notched or ribbedprofile of the fastener ends when they are inserted and advanced throughthe slots. The slots could also be spaced for the purpose of aligningthem with the intercostal spaces (the space between ribs at the juncturewhere they meet the sternum). In addition, the slots could be placed onwinged tabs incorporated into the plate design that extend slightly pastthe sternum and over the intercostal spaces allowing the easy passage offasteners around the posterior aspect of the sternum connecting to theplate on both sides through the slots. The winged tabs might be bendableto adapt to the surface of the bony anatomy when the fasteners aretensioned. In an alternative embodiment, the plate is porous havingperforated holes to allow body fluids to pass through and around theplate.

When secured in place the device assembly supports and holds thesurgically cut bones and their attachments in anatomical approximationeffectively holding closed the chest wall by compressing together alongthe cut or fractured bone surfaces promoting reduced pain or pain freehealing of the sternum and surrounding tissues while at the same timeallowing the flexibility for the chest cavity to expand and contractduring breathing, coughing and other physiological loading. Thefasteners interact with the sternum plate by attaching to it through theslots and compressing the device assembly around the bony fragments whentensioned bringing the surgically cut bone ends into direct contact topromote biological healing with bony union.

Without any intention of setting limitations on the breadth of theinvention described herein and encompassed within the accompanyingclaims, herein provided are descriptions of drawings of the non-limitingpreferred embodiments of the inventive device.

FIG. 1 shows a frontal view of the sternum 11 and a plurality of ribs13. Typically a cut 15 is made in the sagittal plane along the midlineof the sternum 11 longitudinally allowing the separation of the sternum11 and rib cage attachments left and right. The device is to beimplanted at the time of closure allowing the separated segments of thesternum 11 to be anatomically re-approximated and compressed together topromote bony union and healing of the surrounding soft tissues whilereducing or eliminating pain, infection and potential of non-union. Theinvention could also be used to repair and reconstruct the chest wallfollowing traumatic injury sustained as a result of fracture(s) to therelative bony structures. This FIG. 1 thus merely shows the prior artsituation of a surgically cut sternum in need of some type of connectionto promote healing.

FIG. 2 thus shows a first embodiment of the invention 31 comprises aplate 33 that is placed over the sternum 11 and is secured in positionin a splint-like fashion with a plurality of self locking fasteners,such as zip ties, passed behind the sternum 11 through the intercostalspaces 17 and attached and secured to the plate 33 through correspondingslots (also referred herein as holes or apertures) 35 in the plate 33with some or all incorporating a locking mechanism which grips and locksaround the notched or ribbed textured surface of the fastener ends. Whensufficiently tightened the plate and fastener assembly compresses theplate, fasteners and the bony fragments snugly together in anatomicalposition reducing pain and promoting postoperative healing of the boneand surrounding tissues. As noted above, this fixation modality isdescribed herein as “circumfixation.”

FIG. 3A shows a rear view of the first embodiment of the invention,showing a plurality of torsion rails which stiffen the plate whileproviding reduced surface area contact with the underlying bone.

FIG. 3B shows a side view of the first embodiment of the invention.

FIG. 4 shows a rear view of the first embodiment of the invention 31,showing a plurality of perforations 37 though the plate body 33, torsionrails 41, 43 and apertures 45 through which fasteners may pass.

FIGS. 5 and 6 show a dual plate embodiment having a male plate 501 and afemale plate 521. The male construct 501 possesses a plurality offastener straps 505 extending from the plate body 503. In thisparticular embodiment, the male plate body 503 possesses a plurality ofapertures 507 allowing the passage of fluids through the plate. Theplate body 503 also possesses a plurality of elongated protrusions or“torsion rails” 511 running up and down as well as a plurality oftorsion rails 513 running across the body 503. The female construct 521possesses a plurality of torsion rails 533 and 531 which increase theplate body 523 rigidity and reduce the total contact surface area withthe tissue being secured by the plate. A plurality of apertures 525,each possessing a self locking mechanism receive the male fasteners 505of the male construct plate construct 501. The apertures 525 are bepositioned, preferably, out on protruding sections or wings 529 of thebody 523.

This type of circumfixation is referred to as circumfixation method“type B.” Whereas the first embodiment and method described the use of aplate and multiple independent locking fasteners to create a fixationconstruct, the “type B” method does not employ independent lockingfasteners, rather, the fastening feature is incorporated into the platebody geometry 503, 523 resembling phalanges extending from the body ofthe plate. Locking phalanges 505 extending from the body of the plateherein referred to as “male” plate body are joined to a second platebody with corresponding locking slots 525 designed to accept and securearound the profile of the locking phalange fastener ends herein referredto as “female” plate body when they are inserted through the lockingcorresponding locking slots. The size, shape, thickness, strength,stiffness and material composition of “type B” circumfixator platebodies and the quantity, size, strength and flexibility of the lockingphalanges and receptor locking slots will vary depending on a number offactors including the intended purpose, anatomical location; the sizeshape, quality and quantity of the bone, bone segments and fragments,etc.

Such a construct might be favorable for fixing or splinting bones roundor tubular in shape, including ribs, the spine, femur, tibia, fibula,radius, ulna, humerus, carpels, metacarpals, phalanges, tarsals,metatarsals, clavical, and the like. Such a construct might also proveideal for fixing or splinting peri-prosthetic fractures, variouspediatric fractures and osteotomities, and fixing and/or splinting in orover joint areas including the hip, knee, ankle, wrist, elbow, shoulder,spine, fingers and toes.

FIG. 7 shows another embodiment 601 of the invention possessing notorsion rails. This version possesses a thinned horizontal section 609allowing flexion of the sternum plate 603 along the sternum andmanubrium border.

Fasteners 71, 83 could have single ended locking capability as shown inFIG. 9 or a double ended locking capability as shown in FIG. 10.Likewise plate slots could be locking or passive (non-locking). Undersuch a scenario whereby the slots incorporated into the plate arepassive and do not contain the locking mechanism necessary to lockaround the fastener profile, a special locking nut or “donut” could beutilized to achieve the same purpose. A locking nut is slipped over afastener that has been inserted through a passive plate slot and slippeddown around the fastener profile until it meets the plate surface at thejunction where the fastener 711 and the passive plate slot 703intersect. The locking nut would contain a locking mechanism allowing itto grip around the profile of the fastener and prevent the fastener frombacking through the slot. The fastener could be tensioned by advancingit through the slot and locking nut allowing for a snug and secureclosure. After final tensioning, the excess fastener body would betrimmed and removed just above the top of the locking fastener where thefastener body exits the locking nut.

A single-ended fastener could have a head 73 at one end that stops andrests flush when it meets the surface of the plate after it is threadedthrough a non-locking slot and tensioned when the locking end of thefastener is passed through the corresponding or opposing locking slot onthe contralateral side of the plate and thereafter tensioned. The distalend 75 of the fastener will lock after threading through the distalplate slot and thereafter tensioned. A double-ended fastener 81, wherebyboth ends offer the capacity to be simultaneously tensioned and lockedthrough opposing plate locking slots, could be beneficial to achievingeven tensioning of an implant construct. This would apply to plate slotscontaining a locking mechanism or passive slots and the use of lockingnuts. The surface geometry of the fasteners could be square, as shown inFIG. 21A, rectangular (flat), or rounded as shown in FIG. 21B. A roundedor hexagonal surface may possess less of a potential to irritate thebone and adjacent soft tissues under tension and physiological loading.All potential fastener geometries are better able to evenly distributetheir forces across a larger surface area compared to wire which shouldreduce the potential for irritation and infection. Fasteners may also becannulated allowing the insertion of a guide wire through their core tofacilitate their passage through soft tissues, muscle and cartilageencountered around the sternum at the time of placement. Alternatively,fasteners might incorporate a cardiac needle affixed on one end to aidin their passage through soft tissue, muscle, and cartilage found aroundthe sternum. After tunneling through the soft tissue, muscle and/orcartilage the cardiac needle can be severed from the fastener anddiscarded.

Cannulated handles 91 as shown in FIG. 11 could be temporarily attachedto the fastener ends 75, 83 or 85 once they are threaded throughopposing plate slots giving the operator a means of tensioning thefasteners in position by pulling on the handles. Cannulated handles 91could be made of metal or plastic and might have a threaded nut/ring 93around their barrel 95 that when tightened reduces the cannulationaperture allowing them to attach to fastener ends for tensioning andmanipulation. Upon un-tightening (or loosening) of the threaded nut/ringthe handle can be easily removed. Cannulated handles could be used onsingle- or double-ended locking fasteners also with or without the useof locking nuts. By pulling on cannulated handles attached to thefastener ends the device assembly surrounding, the bone fragments can bemanipulated allowing the bone fragments to be reduced into anatomicalposition and securing the device assembly in position by compressing theplate and fasteners around the bony fragments.

The plate and fastener assembly must be sufficiently strong to withstandthe biomechanical forces typical under normal and severe functionalloading conditions. In the preferred embodiment, the implant materialwould be biocompatible, light-weight, radiolucent and easily removableshould emergency surgical re-entry through the chest wall be necessary.An ideal method of removal would be the ability to release the fixationwith a common pair of surgical scissors by cutting through the fastenersallowing the plate and fasteners to be quickly and easily removed.

As shown in FIG. 12, the plate 33 may be configured with rigid orbendable flaps or wings 39 with the slots located within to facilitatesimplified placement of the fasteners. Due to anatomical differences ofdifferent statured patients it might be necessary to offer multiplesizes of plates to properly conform to the variable anatomy.

Preferably the fasteners have a rack of ridges resembling zip-ties. Inthe preferred embodiment the fasteners could lock through corresponding“female” slots incorporated in the plates 33 each slot containing alocking mechanism that prevent the fasteners from backing out after theends are threaded through slots. Alternatively, fasteners could besecured with locking nuts that each contain a locking mechanism andsecure the fasteners in position when advanced along the outer profileof fasteners once they have been passed through passive or non-lockingplate slots and firmly pressed up against the plate slot interfacerestricting the fastener from backing through the plate slot. There aretwo major types of fasteners: single ended locking and double-endedlocking. FIG. 9 shows the single ended locking fastener (SELF) 71 whichhas a head 73 on one end that prevents it from pulling through anon-locking slot and has a textured surface 77 on the opposite end 75that allows it to mesh with the locking mechanism contained in thecorresponding locking slot preventing it from backing out whentensioned. The second type of fastener would be the double ended lockingfastener (DELF) 81 whereby both ends of the fastener 83, 85 can belocked through slots containing locking mechanisms. In an alternativeembodiment of either type of fastener, the fastener has a cardiac needlefused to one of the male ends through a molded in process or suture tie.The use of cardiac needles will allow the operator to easily pass theattached fasteners through the soft tissue, muscle and cartilageadjacent to and surrounding the sternum. The fasteners are placed behindthe sternum and emerge through the intercostal spaces on both sides ofthe sternum and attached to the plate by threading through the slots.Before or after the male end is threaded through the female slot withlocking mechanism the cardiac needle can be removed from the end and thefastener can be tensioned pulling the sternum fragments closed. Once thechest wall is sufficiently closed the excess fastener end can be trimmedback and removed leaving the fastener flush at the surface of thelocking slot. Alternatively, a special cannulated awl could be used totunnel under the sternum easing the passage of fasteners without the useof cardiac needles.

The cannulated tensioning handle can be used to tension the fasteners toenable closure of the open sternum. This is done by engaging the end ofthe fasteners with the handle so that the handles can be pulled withhuman power to provide tension on the fasteners pulling against thestrut plate and close the sternum. After tensioning the handles can bereleased from the fasteners and the handles can be disposed.

The sternum plate covers the sternum body and manubrium and is affixedto the bony anatomy with zip tie-like strap fasteners that pass behindthe sternum and lock to or through the plate that is placed on theforward facing aspect of the sternum and manubrium. When secured inplace the device assembly supports and holds the surgically cut bonesand their attachments in anatomical approximation effectively holdingclose the chest wall by compressing together along the cut or fracturedbone surfaces promoting reduced pain or pain free healing of the sternumand surrounding tissues while at the same time allowing the flexibilityfor the chest cavity to expand and contract during breathing, coughingand other physiological loading. The fasteners interact with the sternumplate by attaching to it through the slots and compressing the deviceassembly around the bony fragments when tensioned bringing thesurgically cut bone ends into direct contact to promote biologicalhealing with bony union.

FIGS. 13 and 14 show a dual plate embodiment of the invention where afemale circumfixation plate 101 and a male circumfixation plate 121 maybe joined and fastened around a bone or bone fragments to aid in thestabilization and union of the bone. The female plate 101 possesses aplurality of apertures 103, each aperture having a self locking fastenermechanism. The male plate 121 possesses a plurality of fastener straps125 built into and extending out from the plate body 123. The male plate121 may be positioned upon one side of the bone, or bone fracture, whilethe female plate 101 is positioned upon the opposite side. The fastenerends 125 are fed through the apertures 105 and tightened to secure theplates 101, 121 together. The excess fastener end 125 may then beremoved so the remaining end of the implanted fastener is flush with thefemale plate body 103.

FIG. 15 shows the sternum 11 and yet another embodiment 801 having aplurality of closely spaced apertures 805, or slots positioned along theleft and right sides of the plate body 807. Due to the variability ofpatient specific rib spacing such a design may be more practical byproviding the operator more options to dock fasteners to the sternumplate.

FIG. 16 shows a cross section of the sternum and invention taken on line1616 from FIG. 2. The torsion rails provide for a reduced surfacecontact area with the bone, allowing increased circulation of bodilyfluids to the bone and other tissues. The torsion rails also provideadditional stiffness to the plate.

An alternative embodiment of the invention comprises of a flexiblefastener, strap-like device, resembling a zip tie or cable tie. Thefastener could be double ended, as shown in FIG. 17, where either endmay be fitted into a ratcheting fastener or single ended, as shown inthe partial view of the fastener in FIG. 18, 19, or 20. A single endedfastener such as FIG. 18, 19 or 20 would have a head at one end that mayor may not have a slot with locking mechanism contained within thatsecures around the fastener profile resisting pullout when the texturedand tapered opposite end of the fastener is inserted through the slotforming a closed loop. FIG. 18 shows a fastener without such a lockinghead, instead a widened head 407 provides a stop. FIG. 19 shows afastener with such a locking head 447. FIG. 20 shows a section view ofthe fastener shown in FIG. 19 taken along line 20-20 showing a flexiblecam or prong 449. A single ended fastener might also appear aspreviously described but without head or terminal endpoint 447 allowingit to join or be locked to another body containing a correspondinglocking slot. A double ended fastener, as shown in FIG. 17, would betextured 207 and tapered at both ends 203, 205 allowing both ends tolock to another body or bodies when passed through corresponding lockingslots or locking fasteners.

The cannulated core or canal 211 that extends from one end of a fastenerbody to the other along the long axis of the fastener is to allow thepassage of a guide wire to aid in their insertion though soft,semi-dense, and potentially hard material such as various connectivetissues, muscle, cartilage and bone. A guide wire, as shown in FIG. 17,with a “stop” 310 would allow the cannulated fastener to be advanced bypulling on the lead end 303 of the guide wire 301 allowing a cannulatedfastener with a specially tapered tip at the lead end 203 to follow theguide wire tunneling through soft, semi-dense and potentially densematter encountered along the pathway. A stop feature 310 incorporatedinto a guide wire 301 would prevent a guide wire from traveling freelypast the trailing end 205 of the fastener 201 and entirely through thecannulated canal such as would happen with a guide wire without a stop.When passing a guide wire 301 with a stop through the cannulated canalof a fastener, the advancement of the guide wire through the canal islimited when the stop feature 310 incorporated into the guide wire meetsthe fastener end preventing the guide wire from freely passing throughthe cannulated canal and completely exiting the opposite end of thefastener. This is due to the stop 310 being larger in diameter than thecannulation aperture restricting the stop 310 and the trailing end ofthe guide wire behind it from entering the cannulated canal of thefastener. The stop 310 is placed along the guide wire in such a locationas to allow a portion of the guide wire to extend beyond the tapered tipof the leading end of the fastener when fully inserted into thecannulated fastener at which point the stop is resting against thecannulated opening at the trailing end of the fastener. Thus, when aguide wire with stop 310 is fully inserted into a cannulated fastener,resistance results when pulling the exposed end of the guide wire at theleading end emerging from the cannulated canal at the leading end of thefastener. When the guide wire 301 is tensioned in this way and enoughforce is applied the fastener advances along with the guide wire. Once acannulated fastener 201 has been advanced to a desirable restingposition, the guide wire is no longer needed and is removed by graspingits exposed end at the trailing end of the fastener and pulling itcompletely from the cannulated canal 211 of the fastener and discarded.The specially tapered tip on the lead end of the fastener can be cut andremoved thereafter. The tapered tip would preferably have a squarepyramid tip, FIG. 22A, a triangular pyramid tip, FIG. 22B or a conicalshaped tip, as shown in FIG. 22C. Such tip profiles could be equallysuited for the fastener lead end and in the case of the double endedfastener, its trailing edge.

Such fasteners could be made of a thermoplastic polymer such as PEEK,nylon or resorbable polymer formulations. Potentially they could also bemade of metallic materials including stainless steel, titanium, cobaltchrome and other alloys. They could be made of solid or braided materialto enhance their malleability. Guide wires are typically made ofstainless steel but could be made of other materials. Their diameter canrange depending upon the dimensions of the fastener they are to beutilized with and strength requirements due to the density of thematerial they are intended to assist fasteners to tunnel through. Thecannulated fastener may have a rounded profile as shown in FIG. 21A toavoid sharp edges, or may have quadrilateral profiles as shown in FIG.21B.

Cannulated fasteners would be very useful in minimally invasive“keyhole” surgery where visibility and access are limited. Cannulatedfasteners are a valuable component of circumfixation constructsdescribed above. Cannulated fasteners may be used with other fixationdevices such as plates, rods, nails and wires.

Cannulated fasteners might have barbed exterior surfaces, 273 or 283,allowing them to be inserted in one direction but resistant to pull outin the opposite direction.

The cannulated fasteners guide wire allows insertion of fastenerswithout the aid of a pilot hole. Under some conditions, a pilot hole maybe useful to enter through extremely dense material. Guide wires are, asin the preferred embodiment, smooth, but in an alternative embodiment, athreaded tip may be present to guide in their insertion through densematerial.

Alternatively, a cannulated fastener might be aided in its placement bya mechanical instrument 501, such as shown in FIG. 23, that when theprobed end of said instrument is inserted into the cannulated canal asshown in FIG. 24, of the fastener allows an operator to manipulate andguide a fastener to bend and move in a desirable direction. This isaccomplished by the fastener being flexible and malleable, especially inone plane. For example, bending along the fastener's 201 wider crosssection thickness provides less overall curvature, while bending alongthe fastener's thinner cross section thickness allows the tool andfastener to be bent in the desired direction. This capability may provevaluable in a variety of applications including minimally invasive or“keyhole” surgery where direct and indirect visualization is eitherlimited or lacking completely. Such an instrument might also incorporatean imaging capability such as fiber optics giving the operator thecapability of indirect visualization of the pathway the device andfastener are traveling.

The above embodiments possess single ended and double ended lockingfasteners which are connected to circumfixation plates through speciallydesigned slots incorporated into the plate body. Each slot within theplate body designed to self lock contains a locking mechanism thatsecures around the fastener profile when inserted and advanced through aslot from one direction and resistant against pullout when force isapplied in the opposite direction.

An additional embodiment of the invention is shown in FIG. 25 securinglocking fasteners whereby the locking mechanism is not contained withinthe plate body or incorporated within the specially designed slots, orapertures 703, formed in the plate that accept the fastener profile whenthe fastener 711 inserted. This method involves the use of a locking nut731 with a slotted center core 733 containing a locking mechanism withinthat when passed over the profile of a locking fastener 711 locks aroundthe profile, preferably engaging textured ribs 713 molded into the sidesof the fastener 711. Fasteners 711 can be advanced passively throughlocking nuts 731 in one direction but are resistant pullout afterinsertion when force is applied from the opposite direction. Suchlocking nuts 731 could be used with locking fasteners 711 andcircumfixation plates 701 whereby the slots 703 contained in the plates701 do not possess locking mechanisms integrated into the plate body 701and locking fasteners 711 can travel forward and backward through theslots 703. Locking nuts 731 would be placed over the locking fastener711 ends 715 after they are inserted through the passive slots 703contained in a circumfixation plate 701.

FIG. 26 is a perspective view of an example of a locking fastener 731.In this embodiment, locking tabs 705 are positioned on opposing sides ofthe nut 731 aperture 707. While two locking tabs 705 are used in thisembodiment, a single locking tab, or a plurality of tabs may be placedaround the nut 731 aperture 707.

FIG. 27 shows a top view of the locking nut 731. The locking tabs 705can be seen on opposing sides of the aperture 707.

FIG. 28 is a cross section taken on line 28-28 of the locking fastener731 shown in FIG. 27. The locking tabs 705 are shown as protruding fromthe locking nut 731 body 735. These locking tabs 705 engage texturedribs 713 of the fastener 711.

FIGS. 29 and 30 depict another potentially preferred embodiment of theinvention, in this alternative a multi-fastener circumfixation device710 including a sternal body plate assembly consisting of a plate havingexpanded portions 712, 712A, and narrowed portions 714, 714A, a cabletie-like fastener 716 and a locking insert 720. The fastener 716 andlocking insert 720 will be further described below. The plate isdesigned to lie on the relatively flat anterior surface of the sternalhalves and to be “splinted” to the bone by the fastener 716 which isinserted through the soft tissue between the ribs on the first side inan anterior-to-posterior direction, wraps underneath both sternalhalves, is then inserted through the soft tissue between ribs on thesecond side in a posterior-to-anterior direction and finally insertedthrough the locking insert 720 and tightened. The fastener 716 is heldin place by a rotating button 718 present within one expanded portion712 of the plate opposite of the locking insert 720 present within theopposing expanded portion 712A. FIGS. 29 and 30 show the fastener afterit has been tensioned and the excess length cut off. The significantfeatures of the plate are:

The expanded portions 712, 712A of the plate 710 correspond to theintercostal spaces in the sternal body. The width of the plate acrossthese wings is still significantly less than the width of the sternum.This allows/forces the fastener 716 to exit the plate and reenter thelocking insert 720 at an oblique angle that is closer to being parallelwith the anterior surface of the sternum. As the fastener 716 istensioned through the locking insert 720, the force vectors provide agreater force in the medial-lateral direction and a lesser force in theanterior-posterior direction. The result is more of the tensioning forcesqueezing the sternal halves together. Contrast this with FIGS. 16 and25, above, where the force vectors resulting from tensioning thefasteners serve to primarily compress (splint) the plate to the sternalhalves without adequately addressing the need to compress the sternalhalves to promote stability and healing.

Such a plate 710 is thus designed to be more flexible along the midlineallowing the wings to flex and conform to the anterior surface of thesternum as the fastener(s) 716 is tensioned. The expanded portions 712,712A in the plate 710 can thus be sized and located to optimizeflexibility and provide visualization of the sternotomy gap.

Cavities in the expanded portions 712, 712A allow for placement of thebutton end 718 of the fastener 716 and the locking insert 720. Tabs 717,717 a on the plate 710 mate with grooves 719, 719 a on the button 718and the locking insert 720 to insure correct orientation and to provideretention.

The button 718 (and the fastener/strap 716) and the locking insert 720can rotate within the cavities of the plate 710 to allow thefastener/strap 716 to adjust to the sternal anatomy. It is not alwaysfeasible to have every wing (expanded portion 712, 712A) on the plate710 fall precisely between the ribs or where the sternum is most narrowand this rotation allows the plate assembly to adjust to the particularpatient anatomy while still providing for optimal tensioning of thefastener 716. Additionally this rotational adjustability should reducethe number of discreet plate sizes/configurations required for thepatient population.

The underside of the plate, as shown in FIG. 31, for instance, alsocontains some notable features: small projections 715 along the midlineof the plate can be included to maintain plate position duringimplantation. Shown on this illustration are a series of thin “keels”715 intended to engage the sternotomy gap to maintain the midlinepositioning of the plate as the fasteners 716 are being tensioned. Thesize, shape and number of these keels 715 could be optimized to maintainplate position without adversely affecting the implant's ability tocompress the sternotomy gap. In another embodiment, these keels 715could be replaced by small spikes or a textured underside to provide therequired stability. In this embodiment the central underside of theplate 710 is relieved. This promotes flexibility of the wings 712, 712Aas noted above and minimizes direct contact of the plate and the healingsite along the sternotomy line. The underside view of the plate 710shows the oblique entry and exit paths of the fastener/strap 716 as wellas the angulation provided by the rotatable button and lock.

FIG. 32 illustrates the fastener/strap 716 prior to installation in theplate. At the top end is an integral needle like tip 738 for piercingthe soft tissue in the intercostal spaces. At the opposite end is thebutton 734 which retains the fastener in the plate and allows forsubsequent rotation. In between is the body of the strap 736. In theembodiment where the fastener is a solid cable tie-like strap the bodyconnects the needle end to the button. In another potentially preferredembodiment where the fastener is a braided/woven design, the braid/weaveextends from the button to a short, solid transition area proximal tothe needle end. This allows the surgeon to cut the needle off once ithas been used to pierce the soft tissue and still have a solid end forease of insertion through the plate and locking insert. There are amultitude of braided or woven configurations known to those skilled inthe art.

Braided materials can be constructed of many different materials, frommetals to polymers and designed to produce optimal balances offlexibility and tensile strength. Such materials require the need for asolid transition element in a braided construct, as the cut ends frayunacceptably if cut and not fused. The significant features of a braidedfastener include improved handling for the surgeon. The braided fastenerwould be more flexible and resemble a heavy suture more than asemi-rigid strap. The greater flexibility of the braid would allow it tobetter conform to the irregular surfaces of the sternum as it is wrappedaround and tensioned. The resulting greater contact area would decreasethe local areas of stress in a bone plagued by poor cortical density andthickness. Greater flexibility will result in fewer and smaller gapsbetween the fastener and bone as it negotiates tight bends and curves.This results in more predictable tensioning and less unwanted movementpostoperatively.

A braided fastener has an intrinsic surface texture for engagement witha locking mechanism employing teeth to grip the fastener and preventreverse motion. Such a braided fastener further offers greater patientsafety upon removal. Unlike conventional wire or the Synthes ZipFix, thecut end of a mesh fastener would produce a soft, frayed end on aflexible strand. Contrast that with a sharp cut end on a semi-rigid wireor ZipFix and consider them being pulled blindly around the back side ofthe sternum for removal. A braided fastener may also prove to be sobeneficial that some surgeons may wish to use a locking braided cabletie alone, in place of wires, ZipFix, the “circumfixation plate” or evenas the means of securing the manubrium when used in conjunction with the“circumfixation plate”. Such a device would itself be novel andvaluable. Combining the fastener button with the insertion lock producesjust such a device as shown below in FIG. 8.

FIG. 33 provides a different type of a potentially preferred fastener716A for utilization with the plate 710. This alternative fastener 716Aincludes a piercing needle tip 748 and a body portion 746, but the otherend is a locking mechanism 744.

FIG. 34 shows a profile view of a potentially preferred lockingmechanism 820 for utilization within a plate. Such a mechanism 820includes a shoulder 822 for retention within a plate, a top surface 824,and a one-way locking tab 826 with teeth 830 to grab a fastener end wheninserted through an oblique slot 832 adjacent thereto. In cross-section,FIG. 34A shows the same locking mechanism 820 providing a view of theoblique slot 832. FIGS. 35 and 35A thus show the overall single platestructure 910 with the locking mechanism 920 and retention button 918present within the coverage plate portion 912 with the strap 916 lockedtherein (and thus to a degree that would permit retention around asubject sternum and a single set of interstitial spaces. The fastener916 may be cut to the level of the plate surface 912 if desired.

A double wing plate 930 is provided in FIG. 36, including said two wings932, 932A and a single narrowed portion 934, 934A with two fasteners 936and two sets of buttons 938 and locking mechanisms 940, as above. Thiswould allow for coverage of a greater area of a subject sternum withsecured fastener attachment through and around two interstitial spacesets.

FIGS. 36 and 36A thus depict a revolving lock (locking insert) 940. InFIG. 36 you can clearly see the groove (cutout) which mates with thesnap-fit tab on the plate to provide retention, alignment and limitsrotation as desired. The section view illustrates the spring loaded,uni-directional locking mechanism, similar to that found on anindustrial cable tie. The utilization, then, of even larger wingedplates may be employed, if desired, or a series of single or doublewinged structures may be utilized to effectuate the necessary sternumfixation in this manner.

FIGS. 37 and 38 illustrate (one from the top, the other from the bottom)another configurations that may also be potentially preferred forattachment of a splint to a subject sternum. The exact size and shape ofthe plates is less important than the concept of multipleconfigurations—not just multiple sizes. FIG. 37 shows, again, a singlewing configuration 1010 with a base 1014, a fastener receiving slot1020, a one-way rotating cam with a drive socket 1018 (here a hexagonaltype as in FIG. 38, for instance). The plate 1010 includes a top portion1112 that may snap into place to secure the fastener 1016 that isintroduced through securing slot 1120 and a separate, opposite securingslot 1122. Importantly, as noted above, multiple numbers of such snap-onsecuring plate structures 1110 may be utilized along the subject sternumfor fixation purposes. In such situations, then, a one or two fastener“mini-plate” for the manubrium might be an ideal complement to a sternalbody plate. Since the manubrium is often the best bone in the sternumand the first line of defense against the medial-lateral separation ofthe sternotomy post fixation, such fixation in that area is potentiallythe best for this purpose.

FIG. 38A shows the cam-type snap-on plate structure 1110 with the topcover 1112 with snap bosses 1114, and including an access hole 1126 forhexagonal tool (not illustration) insertion and an upper slot 1120. Thecam 1118 is provided to allow access to the complementary hexagonalportion (for the tool insertion) (1156 of FIG. 42, for instance) that isplaced within a tooth-springed tab 1130 to allow for one-way rotationvia a cavity 1136 that allows spring tab deflection during cam rotation(situated within the lower portion 1116). The lower portion 1116 alsoincludes recesses 1134 for snap introduction, and an exit slot 1128 forthe fastener 1111. FIG. 39 shows the underside of the entire plate 1110with the snap bosses 1114 in place within the recesses 1134 and the cam1118 in place within the tooth-spring tab 1138 and the deflection cavity1136. The exit slot 1128 leads to the base slot 1132 for the fastener1111, as well. FIG. 40 provides a view of the top of the entire plate1110 with the top cover 1112, the hexagonal recess 1118 and the cam 1138(teeth at least). FIG. 41 thus shows a side view of the plate 1110 witha raised hexagonal recess 1118, the fastener 1111 introduced therein andthe side wall 1116 protecting the internal portions.

FIGS. 39 and 39A thus depict a fixed angle (no rotation) design with anauxiliary locking mechanism. In addition to the locking mechanism foundin the revolving lock (FIGS. 36 and 36A), the flexible fastener is fedback over a sharp or toothed prominence and captured from above with atab that folds down and locks in place (particularly to capture a cutend of a fastener with great reliability).

FIGS. 40 and 40A thus illustrate an additional locking mechanism for afastener which utilizes a one-direction rotating cam to clamp down onthe braid (or like structure). In practice, the fastener 1111 is fedthrough the front slot 1122 at the bottom and exits through the top slot1128. The cam 1118 is in the neutral (or zero interference position).When the fastener 1111 is properly tensioned, the cam 1118 is rotated(in a clockwise manner) to crimp the fastener 1111 (again, such as abraid structure) between the teeth 1138 on the wall of the base plate1116 and the vertical splines on the cam 1118. A spring loaded pawl 1136molded into the base plate 1116 prevents reverse rotation of the cam1118.

FIG. 42 shows the cam 1118 in greater detail. An internal hex drivesocket 1156 extends from a hub 1150 (upper and lower) with fasteningengaging external teeth 1152 and one-way motion external teeth 1154.FIG. 43 provides a more succinct view of the underside (internal) topcover 1112 with snap bosses 1158 (with barbed distal ends) to snapwithin the recesses of the lower portion. An opening 1126 for insertionand extension of the cam (1118 of FIG. 42) is provided, as well as anexit slot 1120 for the fastener (1111 of FIG. 40). FIG. 44 shows thesame top cover in side view. FIG. 45 provides the top view of the topcover 1112 with the snap boss external portions 1114 to allow for properalignment of the two portions.

Another alternative, potentially preferred embodiment of this singlewing structure is provided in FIGS. 46-47. Such a structure 1210 allowsfor a fixed angle, single fastener device 1211 introduction with asecondary locking mechanism 1216. The mechanism is present on the topcover base 1212 with an exit slot 1218 (and multiple recesses for snaps1214). The locking mechanism 1216 thus engages the fastener 1211 uponintroduction therein through angled teeth. FIG. 47 shows the samestructure 1210 in side view.

For this invention, then, the term “locking mechanism” may be of anytype as described above or that provides effective and reliableretention of one end of a fastener. With the cam device, describedabove, the single direction rotation corresponds to tightening of thefastener without any possible relaxation, thereby locking and tighteningsimultaneously. Additionally, such described locking mechanisms(rotating, fixed, secondary, and cam) may be properly utilized inconjunction with a double-ended fastener for even greater reliability.As alluded to above, as well, all such components and devices can beproduced with any proper materials for resiliency, flexibility, etc., asneeded, and that is acceptable for such “implant”-type structures withinthe human body. The fasteners and the plates may be manufactured of,clearly, different types of materials for such end uses, basically anythat allow for such purposes and, again, that are or may be consideredaccepted and/or approved for implantation and internal splintutilization. As merely examples, then, such a fastener may bemanufactured from braided stainless steel fibers and the plate from apolymer such as PEEK or PEKK, again, as non-limiting examples.Furthermore, the multi-winged plates of, for example, FIG. 37 may bemodified to incorporate a “hinge point” at the sternal angle to providea full-length, properly contoured sternal plate.

Thus, with these different types of structures, all fall within thebasic consideration of fastened sternal plate devices to permit not onlyproper healing subsequent to a sternotomy, but also the ability toprovide flexibility for ribcage movements (such as breathing anddiaphragm requirements) as well as a protective cover for sensitivesternal areas. The different mechanisms described above all providethese benefits, in an area heretofore unexplored within this industry.

Overall, then, as described herein, the technique referred to ascircumfixation could have applications in rib fracture fixation,clavicle fracture fixation, scapula fracture fixation, proximal anddistal femur fixation, proximal and distal tibia fixation, fibulafixation, proximal and distal humerus fixation, proximal and distalradius and ulna fixation, wrist bracing and/or reconstruction, anklebracing and/or reconstruction, spinal bracing and/or reconstruction,pediatric fracture fixation, periprosthetic fracture management andfixation, veterinary fracture fixation and possibly other unidentifiedapplications. Circumfixation could also prove to be a valuable method oftemporarily stabilization of open fractures and comminuted openfractures such as those occurring on the battlefield. The generalinvention thus comprises, in terms of post sternotomy (and the like)surgical procedures, a plate contoured to lie passively against theforward facing aspect of the human sternum when placed directly on theirregular surface of the target sternum, and zip tie-like fasteners tosecure the plate around the target sternum, thus securing the plate tothe target sternum. Thus, the herein described invention allows for areduction post-operative pain for the target patient as well as earlypost-operative mobilization thereof. Such beneficial activities may thuslead to earlier rehabilitation and discharge, and also accord a reducedpotential for infection (as well as a reduced propensity to contracthospital-acquired pathogens). The device is intended to be biocompatibleallowing it to remain in the body permanently, too. The device isintended to be inert and radiolucent causing no interference with anytesting, diagnostic or imaging technology applied to the patientpostoperatively.

The free areas of the plate structures described herein may also beutilized to house different devices for various results, includingtherapeutic activities (such as drug dosing), diagnostic activities(such as heart monitoring), and the like, without limitation, that mightbenefit from such in vivo delivery and that would not interfere with thehealing process. For instance, the delivery of suitable materials to aidin the healing of the sternum in addition to the splint benefitsprovided could be accomplished in this manner.

Furthermore, while the term “circumfixation” in relation to thisinvention is described as a manner for securing and fixating cut orfractured bones avoiding the use of bone penetrating anchors such asscrews, pins, blades, etc. to achieve stabilization, it should be notedthat future designs of circumfixation devices could include the additionof such bone anchors which could enhance and expand the range ofclinical applications of such an activity.

It should be understood that various modifications within the scope ofthis invention can be made by one of ordinary skill in the art withoutdeparting from the spirit thereof. It is therefore wished that thisinvention be defined by the scope of the appended claims as broadly asthe prior art will permit, and in view of the specification if need be.

What is claimed is:
 1. A bone plate assembly, comprising: a plate havinga plurality of apertures formed through the thickness of the plate, withat least two of the plurality of apertures being positioned proximal tolateral edges on opposing sides of the plate; and one or more lockingfasteners each having a first end and a second end opposite the firstend, wherein the one or more locking fasteners can be positioned arounda portion of bone, wherein the first end can be inserted through a firstaperture of the plurality of apertures, wherein the second end can beinserted through a second aperture of the plurality of apertures, andwherein the first end and the second end can each be locked into theplate.
 2. The bone plate assembly of claim 1 wherein the first end andthe second end of the locking fasteners is separately tensionable. 3.The bone plate assembly of claim 1 wherein the one or more lockingfasteners are flexible.
 4. The bone plate assembly of claim 1 whereinthe first aperture and the second aperture each comprise fastenerattachments which resist movement of the locking fastener in a directionopposite an insertion direction.
 5. The bone plate assembly of claim 1wherein each fastener attachment comprises a base slot that accommodatesentry of either of the first end or the second end of the lockingfastener into the fastener attachment to accept and secure the lockingfastener, and an exit slot through which either of the first end or thesecond end of the locking fastener exits the fastener attachment.
 6. Thebone plate assembly of claim 1 further comprising at least one lockingnut configured to be positioned over at least one of the plurality ofapertures and having a hollow core through which either of the first endor the second end of the locking fastener freely passes in the firstdirection, and wherein the locking fastener comprises ribs configured toengage an interior surface of the hollow core, thereby resistingmovement of the locking fastener in the direction opposite the firstdirection.
 7. The bone plate assembly of claim 6 wherein a locking nutis inserted over the first end of the locking fastener mechanism untilit reaches a surface of the plate and a locking nut is inserted over thesecond end of the locking fastener mechanism until it reaches a surfaceof the plate.
 8. The bone plate assembly of claim 1 wherein the lockingfastener is passed behind the sternum, through the intercostal spaces oneach side of the sternum.
 9. The bone plate assembly of claim 1 whereinthe first end and the second end of the locking fasteners is textured.10. The bone plate assembly of claim 1 wherein the first end and thesecond end of the locking fasteners is tapered.
 11. The bone plateassembly of claim 1 wherein the first end and the second end of thelocking fasteners are configured to be received by a ratchetingfastener.
 12. The bone plate assembly of claim 1 wherein the first endand the second end of the locking fasteners are configured to be fittedwith a cardiac needle.
 13. The bone plate assembly of claim 1 whereinthe locking fastener is cannulated.
 14. The bone plate assembly of claim13 wherein the cannulation comprises a channel adapted to receive aguide wire.
 15. The bone plate assembly of claim 14 wherein the guidewire comprises a stop that resists movement into the locking fastener.